I. Field of the Invention
The present invention relates to laminated structures of high bullet resistance, especially transparent ones such as those used as armored glazing.
The term “bullet resistance” is understood to mean, within the context of the invention, a resistance to level BR 3 (caliber: 375 Magnum), BR 4 (caliber: 44 Magnum), BR 5 (caliber: 5.56×45), and up to level BR 6 (caliber: 7.62×51) of the FR EN 1063 standard and also, in particular, to Kalachnikov bullets (caliber: 7.62×39).
The armored glazing referred to is particularly suitable for use as architectural glazing or, in particular, as glazing for armored transport vehicles.
II. Description of Related Art
The laminated structures of high bullet resistance of the invention include a peripheral metal armoring insert introduced into a cavity of the laminated structure, in the extension of and with a spacing from 0.2 to 1.3 mm, of one of its constituent glass sheets.
Moreover, many transport vehicle windows make, on their periphery, a certain angle to the horizontal, for example around 45°. Consequently, a horizontal shot at this periphery will also have an angle of incidence of around 45°.
The inventors have noticed that, under these conditions, a shot fired into the region bounded by the insert, and at a short distance therefrom, especially between 15 and 20 mm, from the inner edge of the insert, is liable to cause damage inside the vehicle. Specifically, it is a region of about 200 mm of glass that absorbs the impact; the polycarbonate usually forming the face inside the vehicle deforms in such a way that glass splinters are liable to be projected into the vehicle.